The installation of abutments and screws within the mouth in implant dentistry is both stressful and hazardous. The mouth has a small opening relative to a dentist's hands, and is a difficult place to work. Implant abutments and screws are difficult to grasp, and great care must be taken that the same are not swallowed or aspirated by the patient.
The screwing of abutments (or posts) onto the implant structure or threading of screws into the bone is conventionally undertaken by small flat or allen head screwdrivers which have shanks and handles sized to fit within the mouth, and which are gripped and rotated within the mouth by the dentist's hand. Such tools have the advantage that the tightening action can be "felt" by the dentist, and carefully controlled. They are, however, difficult to manipulate in such close quarters and, if dropped, can become lodged in the patient's throat. Their use, thus, requires much concentration and is exhausting.
The use of ratchet-type wrenches for installation of abutments and screws is known, though the same offer relatively little advantage over the straight shank direct application screwdrivers. The ratchet action offers less control because is interferes with the "feel" or tactile sensitivity of the installation, and the ratcheting movement introduces undesirable instability in a sensitive procedure. (In ratcheting, the dentist is unable to get the desired tactile feedback regarding torque resistance of the meshing threads, etc.) The use of screwdriver bits on electrical dental handpieces is likewise undesirable because of the complete loss of tactile sensitivity with the attendant risk of either breaking the screw or spinning the implant in the bone.